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TVS diode, also known as transient voltage suppressor or avalanche breakdown diode, is a device used to protect circuits from transient overvoltage impacts. During the selection process, you need to pay attention to the following aspects:

First, it is necessary to clarify the maximum DC value, rated standard voltage value and "high-end" tolerance value of the protected circuit. These parameters are the basis for selecting TVS diodes to ensure that the selected device can withstand the maximum operating voltage and possible transient surge voltages in the circuit.

Secondly, the maximum clamping voltage (Vc) of the TVS diode is less than the damage voltage of the protected circuit. The clamping voltage refers to the maximum voltage value that can be reached at both ends of the TVS under the action of pulse peak current. This parameter is critical to protect components in the circuit from excessive voltage damage. Therefore, when selecting, you need to carefully check the relationship between the clamping voltage of the TVS and the damage voltage of the protected circuit.

At the same time, the rated reverse turn-off voltage (VRWM) of the TVS diode must be greater than or equal to the maximum operating voltage of the protected circuit. VRWM is the voltage value across the device under a specified current when the TVS diode is operating in reverse. At this voltage, the power consumption of the TVS diode is very small. When using it, you should ensure that the VRWM is not lower than the normal operating voltage of the protected circuit.

In addition, after determining the maximum clamping voltage of the TVS diode, its peak pulse current (IPP) should be greater than the transient surge current. The product of IPP and the maximum clamping voltage Vc determines the maximum transient pulse power of the TVS. This parameter is very important to measure the protection ability of TVS. Therefore, when selecting, you need to ensure that the peak pulse current of the selected TVS can meet the transient surge current requirements in the circuit.

In addition to the above key parameters, the impact of temperature changes on the characteristics of TVS diodes also needs to be considered. The operating temperature range of TVS diodes is typically between -55°C and 150°C. When the temperature in the circuit is relatively high, derating is required to ensure the stability and reliability of the TVS.

In addition, depending on the type of circuit, it is also very important to select the appropriate TVS diode type. Most DC protection circuits use unidirectional TVS tubes, and AC protection circuits mostly use bidirectional TVS tubes. For multi-channel protection circuits, TVS array devices can be selected; for high-power protection circuits, dedicated protection modules should be selected.

When using TVS diodes, its discrete nature also needs to be taken into consideration. In order to reduce the impact of discreteness on circuit performance, the number of series/parallel TVS should be reduced as much as possible.